Compressed Air Energy Storage

What is compressed air energy storage, and what does it have to do with TVA's mission?

TVA is interested in new, clean, efficient technologies for generating power. One promising approach is to use power generated when demand is low to compress and store air — underground in salt domes, in underground aquifers, and in depleted underground gas fields; or above ground in pipe or tanks.

When demand for power is high, the compressed air is released, heated and expanded by firing with natural gas and injected into a turbine to generate power.

What is TVA doing about it?

TVA is investigating the use of compressed air energy storage to generate electricity when needed to meet peak demand.

What are the possibilities for the use of stored compressed air for power generation?

Compressed air energy storage is already in commercial use, but the technology is young and still evolving. Its use is dependent on the presence of geology that enables underground storage and the availability of natural gas to fire the air after it is release.

The cost of natural gas is volatile; if it rises too high, the technology could become too expensive to use. Developing new storage fields is also uncertain, with cost overruns possible if the geology of the site makes storing the air underground difficult.

Storage can increase system emissions compared to gas fired peaking units if compressing air off peak increases generation from coal fired units.